Don't run unless your objective is a long ways away. Running gives your position away on map and is irritating to the rest of your team mates. Frag Grenades explode at about 40m away. Handy to know if you are playing skirmish. Aim for the head. I use carbine and pick up either the Marksman or Fareye for secondary when I find them. Pick your berserk carefully. I mostly use ring of life or lark/snake eyes, depending upon number of people in game.
Competitive is awesome once you get the hang of it. Good luck








